Aedes aegypti is the main vector of dengue, Zika, yellow fever and chikungunya viruses, and is a model system for studies of other mosquitoes that vector arboviruses. Current strategies based on suppressing mosquito populations can be effective, but are expensive and require a robust public health infrastructure. The ability to introgress pathogen-resistance genes into mosquito populations has long been sought as a potential alternative for disrupting dengue or malaria transmission where funds and infrastructure are the limiting factors in effective mosquito control. The recent development of effective site-specific nucleases such as homing endonucleases and CRISPR/Cas9 advanced technical solutions to achieving such super- Mendelian introgression, however there are still problems associated with the dominance of end-joining processes preventing the integration and spread of transgenic sequences. In this project, we aim to better understand DNA repair choice in mosquitoes and develop strategies to increase rates of homology-based repair following double-stranded DNA break induction. In Aim1 we will confirm the role of various potential end-joining factors in DNA repair and successful female development, while in Aim 2 we perform temporally-controlled rescue experiments to determine the most critical times during development for end-joining factors. Finally in Aim 3 we will assess the impact of loss of end-joining factors on various forms of homology-dependent repair. The knowledge gained from these experiments will further inform the development of gene drive strategies for vector control as well as provide insight into processes critical for mosquito development and evolution.